This paper presents the results of two experimental studies. The first was a continuation of a 5-year aging study on foil-faced polyisocyanurate thermal insulation boards. These boards were retested in the guarded hot box and represent 11-year aged data. The results indicated excellent agreement with the plateaued R-values established on the 5-year aged samples.

The second effort is an ongoing correlation study between the large-scale guarded hot box and small-scale heat flow meter tests using permeable faced polyisocyanurate foam thermal insulation boards. Thicknesses tested ranged from 2.5 to 8.1 cm (1 to 3.2 in.). The results to date show that, in general, with proper sampling of large-scale boards, good agreement can be expected between guarded hot box and heat flow meter test results.